Problem: Luis has breakfast at a cafe and the cost of his meal is $\$28.00$. He would like to leave a $15\%$ tip. What is his total bill including tip?
Explanation: The tip amount is equal to $15\% \times \$28.00$ We can find the tip by first calculating a $10\%$ tip and a $5\%$ tip, and then adding those two numbers together. To calculate a $10\%$ tip, move the decimal point in $\$28.00$ one place to the left. $10\%$ $\times \$28.00$ $\$2.80$ To calculate a $5\%$ tip, divide the $10\%$ tip amount in half. $5\%$ $\times \$28.00 = $ $\$2.80$ $ \div 2 = $ $\$1.40$ Adding the two amounts together gives us $\$2.80$ $\$1.40 =$ $ \$4.20$ The cost of the meal plus the amount of the tip will equal the total bill amount. $\$28.00 + \$4.20 = $ $\$32.20$ The total cost of the bill is $\$32.20$.